The present invention relates generally to orthopedic appliances, and more particularly provides a uniquely constructed motion restraining knee brace incorporating a variety of improvements over conventional knee braces of this general type.
Following various types of knee injury or surgery, it is often necessary to restrict the pivotal motion of the knee joint to a predetermined angular range extending between an extension limit angle and a flexion limit angle while the knee heals. This pivotal restraint is typically accomplished by securing to the leg a motion restraining knee brace having a pair of articulated side portions positionable on opposite lateral sides of the leg. Each of these side portions is conventionally defined by elongated thigh and calf support members which are pivotally connected at inner ends portions thereof by an adjustable hinge mechanism which is positionable to one side of the knee with its interconnected thigh and calf support members respectively extending longitudinally along thigh and calf portions of the leg on the same lateral side thereof.
The two thigh support members, and the two calf support members, are secured to their associated leg portions by various strap and cushioning pad members which encircle the leg and may be adjustably tightened or loosened against it to hold the support members firmly in place on the leg. The two hinge mechanisms are typically adjustable to selectively limit the relative pivotal motion between the interconnected support members on opposite sides of the leg to thereby limit the pivotal motion of the healing knee to a predetermined angular range extending between an extension limit angle and a flexion limit angle. Thus, for example, if it is medically necessary to restrict the movement of the knee to a pivotal range extending between a 30.degree. flexion angle and a 90.degree. flexion angle, the hinge mechanisms are simply adjusted to limit the relative pivotal motion of each of the interconnected support member sets to this range.
While conventional knee braces of this general type have proven to be quite beneficial in protecting knee joints following injury thereto or surgery thereon, it is well known that such knee braces are subject to a variety of problems, limitations and disadvantages. For example, one such limitation or disadvantage is associated with the need to adjust the overall length of the brace's thigh and/or calf support members to accommodate legs of varying lengths. To solve this adjustment problem, some brace manufacturers simply fabricate their knee braces with thigh and calf support members of varying fixed lengths, and a particular brace size must be selected to generally fit a given leg.
In other conventional knee braces, each of the thigh and calf support members is formed from two adjustably interconnectable longitudinal sections which may be intersecured in selectively variable positions to thereby alter the length of each of the four support members. This adjustment scheme renders it possible to use a single knee brace on legs of varying lengths. However, the interconnection between the two longitudinal sections of each of the support members has heretofore been somewhat awkward and laborious to adjust and has been prone to undesirable slippage. This is particularly true when the two associated support member sections are clamped together or otherwise frictionally engaged with one another. Various removable locking members have also been utilized to provide a more secure interconnection between the two sections, but such locking members are prone to loosening and dislodgment during use of the brace which can result in damage to the knee when the brace subsequently fails to properly restrain its pivotal motion.
Another limitation inherent in conventional knee braces of this general type is associated with the connection of the thigh and calf support members to the leg. Such connection is typically accomplished by connecting straps which are secured to the thigh support and calf support member pairs and are adapted to be looped entirely around the leg and then tightened to securely hold the support members against the leg. With this connection strap structure, however, it is somewhat difficult to properly align the support members in an anterior-posterior sense relative to the particular leg portions along which they extend. More specifically, the use of conventional connecting straps requires that each pair of thigh or calf support members be manually held in proper anterior-posterior alignment with the leg while their connecting strap is looped around the leg and then tightened. If this connection process is not carefully and skillfully performed, one or more of the four support members may be undesirably misaligned with lateral side portions of the leg after the brace has been secured thereto.
Another disadvantage commonly associated with conventional motion restraining knee braces is the difficulty encountered in preventing the leg from being pivotally extended beyond the extension limit angle setting of the brace. Specifically, despite the fact that the interconnected support member sets positioned on opposite lateral sides of the leg are securely strapped thereto, and may pivot only between the angular limits set by their associated hinge mechanisms, the leg itself (because of soft tissue "give") may often be extended somewhat past the extension limit angle setting of the brace. This, of course, to some extent defeats the purpose of the brace.
One solution to this over-extension problem, of course, is to simply set the extension limit of the brace somewhat less than the desired extension limit of the leg to thereby compensate for this soft tissue give. This solution, though, is at best a trial-and-error procedure which must be carefully and skillfully performed because of the variance in soft tissue characteristics among different legs.
Another proposed solution to this over-extension problem has been to provide the brace with a single posterior restraining strap which is interconnected between the side portions of the brace and positioned directly behind the knee joint. By appropriately tightening this restraining strap against the back of the knee, the patient's ability to extend the leg beyond the extension limit setting of the brace is substantially reduced. However, the positioning of the single restraining strap in this manner has proven to be a source of considerable patient discomfort since, as the leg is flexed, the strap interferes with flexion of the leg.
A further proposed solution has been to eliminate the single restraining strap and replace it with two posterior restraining straps respectively positioned longitudinally above and longitudinally below the knee joint. These two straps are designed to provide the extension-restraining function of the single central strap without the patient discomfort associated therewith. However, by moving the two straps away from the knee joint itself, their extension-inhibiting action is significantly diminished. Additionally, it is well known that the extension strength of the human leg progressively increases as the leg approaches its fully extended position. This presents the problem of determining just how much each of these two restraining straps should be tightened against the leg. Specifically, if they are tightened sufficiently to suitably restrain the leg as it approaches the extension limit angle setting of the brace, they will be too tight when the leg is in other positions within the angular setting of the brace.
Finally, the hinge mechanisms of conventional motion restraining knee braces typically present a variety of difficulties in their adjustment and/or their ability to strongly and reliably maintain their angular limit settings. As an example, various conventional hinge mechanisms utilize removable locking pin elements to define angular stops which limit the pivotal motion of one of the support members associated with the hinge. Other conventional hinges utilize various types of movably supported elements which define pivotal stop surfaces for one of the support members. The adjustment of conventional hinge mechanism of this and other types tend to be somewhat cumbersome and time-consuming. Additionally, the possibility exists that the various locking members may be dislodged and lost, or jarred out of position, which can result in hinge malfunction and possible damage to the leg.
From the foregoing it can be seen that conventional motion restraining knee braces are subject to a variety of problems, limitations and disadvantages. It is accordingly an object of the present invention to provide an improved motion restraining knee brace which eliminates or minimizes above-mentioned and other problems, limitations and disadvantages typically associated with such conventional knee braces.